MANCHESTER, Britain, May 23 (Xinhua) -- Britain was placed on the highest terror threat level Tuesday night, less than 24 hours after the country's worst terror attack in 12 years hit Manchester, which left 22 dead and 59 injured.

"I SMELT GUNPOWDER"

"I heard a big bang and then I smelt the gunpowder," Liu Shixuan, a Chinese visiting Manchester, told Xinhua. Liu was staying just 300 meters away from the Manchester Arena where the incident happened.

"The sound was not a thunder. There are no such loud thunders in Britain," she said, adding that police vehicles were seen minutes after the explosion.

"Police copters hovered overhead throughout the night," Liu recalled.

On Tuesday night, helicopters could still be heard hovering around the area.

Police and security forces in Manchester continued Tuesday night to piece together the life of Salman Abedi, 22, the suspected suicide bomber who brought carnage and horror to an arena packed with 21,000 concert goers.

By detonating an improvised homemade bomb he sparked what was Britain's worst terror attack since the London bombings in 2005.

He struck with deadly consequences the moment thousands of happy, smiling fans started to pour out of the 21,000-seat arena after a concert by American singer Ariana Grande.

All night long, and throughout Tuesday some desperate families were still trying to find children caught up in the blast.

As security experts started to forensically build a picture of what happened, the names of some of the dead started to emerge.

Teen Georgina Callander, a rock solid fan of Grande, was the first to be publicly named as a victim. Eight-year-old Saffie Roussis is almost certainly Abedi's youngest victim.

Police are eager to establish whether Abedi was a lone-wolf attacker or part of a terror cell. It quickly emerged that he was born in Manchester, the son of refugees who fled Libya to make a new life in Northern England.

Media reports described how Abedi was a student at the University of Salford in the city that adjoins Manchester.

Security services and government ministers had continually announced a terror attack on Britain was likely, particularly after outrages in mainland Europe. But Britain felt safer, being an island country surrounded on all sides by water, thought to offer some protection against attacks.

What happened at the Manchester Arena Monday night shows that Britain is penetrable.

It is the worst ever peacetime attack in the city that sees itself as the de-facto capital of northwest England. Even when a pro-Irish Republican bomb squad caused havoc to the city center with a huge bomb in 1976, there were no fatalities, only wrecked buildings.

CRITICAL THREAT LEVEL

Prime Minister Theresa May announced Tuesday night in London that the threat level has been raised to "critical", which means further attacks may be imminent.

It also means armed soldiers will be deployed to protect key buildings as well as being on duty at major events.

May was speaking after she chaired the second meeting of the day of Britain's top-level security committee known as Cobra, called in response to the suicide bomb attack at the Manchester Arena Monday night.

Saying she does not want the public to be unduly alarmed about the announcement, May said it was a proportionate and appropriate response to the current threat facing the country.

"We stand defiant ... the terrorists will never win, and we will prevail," said May.

IMPACT ON GENERAL ELECTION, BREXIT

Political leaders, reaching the last two weeks in a critical general election campaign ahead of voting on June 8, called a truce.

In an act of unity they have postponed electioneering across the country. The squabbling and a political war of words have been put on hold as political foes stand shoulder to shoulder in defiance against the attack.

The fact that the suicide bomber Abedi was born in Manchester, the city he attempted to tear apart, became a shocking reminder how terrorism is never far away from home.

It provoked a lively debate on social media with some people speculating that the Manchester bombing worked in favor of May's Conservative government.

Opponents of main opposition leader Jeremy Corbyn, who wants to lead Labour to power, cite his past as an alleged sympathizer of radical groups.

May has presented herself to the 46 million voters in Britain as a strong leader, supportive of Britain's counter-terrorism machine, and also a backer of a so-called snooper's charter to seek out potential terrorists.

May has also adopted a tougher stand on immigration than her Labour rival, Corbyn.

It was a theme taken up by the website, The Slate, which in a commentary said conventional wisdom is that terrorist attacks immediately preceding elections benefit the right and candidates with more hawkish national security policies.

"And that's likely to be the case here," said the Slate's Joshua Keating.

Conservatives had already argued that a victory by dovish leftist Corbyn would "increase the risk of a terrorist attack," said Keating.

However, it is unlikely to make a dent in the Brexit debate on whether May should stick to her guns and deliver the referendum result to bring Britain out of the European Union.

Surveys and polls have shown that terrorism is hardly mentioned as an issue among voters on either side in the Brexit division.

The impact of the Manchester bombing on Brexit will not become clear until parliamentary hopefuls resume their dialogue with voters.

Meanwhile, Alex Westmorland, a first-year student with a local college, told Xinhua that he believed the Manchester blast could "make Brexit worse" because people would naturally assume the links between such attacks with immigrants.

Around 60 percent of voters of Manchester voted for Remain in the Brexit referendum last June.

The start of the snap election campaign made May's Conservative party resembles a runaway train, only to see Labour catch up in the last week to cut May's lead to single figures. Political observers will be waiting to see whether and when the battle resumes.